A conventional air filtering device for a vehicle engine is illustrated in FIG. 1 and generally includes a collar 100 with a tubular neck 101 extending from a top thereof and the tubular neck 101 has a threaded inside so as to engaged with a cap 200 which seals the neck 101. A filtering member 300 is a cone-shaped member and made of a metal netted layer and a non-woven layer. The filtering member 300 is made to have corrugated periphery in order to obtain a larger filtering area when air flowing through the periphery of the filtering member 300. The first end of the filtering member 300 is engaged with the collar 100 and the second end of the filtering member 300 is engaged with a groove 401 of a base member 400. Therefore, air can only flow through the corrugated periphery of the filtering member 300 and the speed of the air flow will be reduced because the direction of the air flow is changed perpendicularly to enter into the manifold which is connected between the engine and the filtering device. The slow flowing speed of the filtered air reduces the efficiency of the operation of the engine especially when the engine runs at a higher revolutions.
Furthermore, the installation of the manifold is always incurred by the deficiency of space. That is to say, the shape and the length of the manifold is designed and installed when all the parts around the engine are positioned so that the conventional manifold generally has a complicated shape including many curve portions. The manifold having the complicated shape further limits the speed of the filtered air flowing into the combustion chamber in the engine.
The present invention is to provide a filtering device which provides more volume of fresh air into the engine and the speed of the fresh air will not be reduced so as to increase the efficiency of the combustion in the engine.